Paper II visual guide · Visual 5 of 24 · MODEL A / COHERENCE AND NATURALITY

The operator changes coordinates too

Traditional paper: Theorem 3.5 (p. 4), Theorem 3.8 (p. 6)

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Use a finite periodic carrier \(X={\mathbb Q}^8\) for this example. Let \(Se_j=e_{j+1\bmod8}\) and let

\[ T=I+2S+S^2. \]

This is a concrete cyclic model, not an unannounced boundary convention for the finitely supported signal on V20. Write \(R_N\) for the permutation that groups coordinates in increasing residue order modulo \(N\).

Three exact eight-by-eight operator matrices
Original drawing. Read the description below; expand the labels and data for selectable text.

Reading the drawing

Rows are outputs and columns are inputs. Heavy rules mark packet blocks. The middle permutation changes the coordinate order, and the last matrix is the same operator in the new coordinates.

Drawing labels and data 196 labels

Read the original labels as selectable text. Tables preserve grid relationships; other short labels are grouped compactly.

  • \(\widehat T_2\)
Drawing grid 1 · rows top to bottom, columns left to right
Row / columnColumn 1Column 2Column 3Column 4Column 5Column 6Column 7Column 8
Row 1\(1\)\(\cdot\)\(\cdot\)\(1\)\(\cdot\)\(\cdot\)\(\cdot\)\(2\)
Row 2\(1\)\(1\)\(\cdot\)\(\cdot\)\(2\)\(\cdot\)\(\cdot\)\(\cdot\)
Row 3\(\cdot\)\(1\)\(1\)\(\cdot\)\(\cdot\)\(2\)\(\cdot\)\(\cdot\)
Row 4\(\cdot\)\(\cdot\)\(1\)\(1\)\(\cdot\)\(\cdot\)\(2\)\(\cdot\)
Row 5\(2\)\(\cdot\)\(\cdot\)\(\cdot\)\(1\)\(\cdot\)\(\cdot\)\(1\)
Row 6\(\cdot\)\(2\)\(\cdot\)\(\cdot\)\(1\)\(1\)\(\cdot\)\(\cdot\)
Row 7\(\cdot\)\(\cdot\)\(2\)\(\cdot\)\(\cdot\)\(1\)\(1\)\(\cdot\)
Row 8\(\cdot\)\(\cdot\)\(\cdot\)\(2\)\(\cdot\)\(\cdot\)\(1\)\(1\)
  • \(J_{4,2}\)
Drawing grid 2 · rows top to bottom, columns left to right
Row / columnColumn 1Column 2Column 3Column 4Column 5Column 6Column 7Column 8
Row 1\(1\)\(\cdot\)\(\cdot\)\(\cdot\)\(\cdot\)\(\cdot\)\(\cdot\)\(\cdot\)
Row 2\(\cdot\)\(\cdot\)\(1\)\(\cdot\)\(\cdot\)\(\cdot\)\(\cdot\)\(\cdot\)
Row 3\(\cdot\)\(\cdot\)\(\cdot\)\(\cdot\)\(1\)\(\cdot\)\(\cdot\)\(\cdot\)
Row 4\(\cdot\)\(\cdot\)\(\cdot\)\(\cdot\)\(\cdot\)\(\cdot\)\(1\)\(\cdot\)
Row 5\(\cdot\)\(1\)\(\cdot\)\(\cdot\)\(\cdot\)\(\cdot\)\(\cdot\)\(\cdot\)
Row 6\(\cdot\)\(\cdot\)\(\cdot\)\(1\)\(\cdot\)\(\cdot\)\(\cdot\)\(\cdot\)
Row 7\(\cdot\)\(\cdot\)\(\cdot\)\(\cdot\)\(\cdot\)\(1\)\(\cdot\)\(\cdot\)
Row 8\(\cdot\)\(\cdot\)\(\cdot\)\(\cdot\)\(\cdot\)\(\cdot\)\(\cdot\)\(1\)
  • \(\widehat T_4\)
Drawing grid 3 · rows top to bottom, columns left to right
Row / columnColumn 1Column 2Column 3Column 4Column 5Column 6Column 7Column 8
Row 1\(1\)\(\cdot\)\(\cdot\)\(\cdot\)\(\cdot\)\(1\)\(\cdot\)\(2\)
Row 2\(\cdot\)\(1\)\(\cdot\)\(\cdot\)\(1\)\(\cdot\)\(2\)\(\cdot\)
Row 3\(2\)\(\cdot\)\(1\)\(\cdot\)\(\cdot\)\(\cdot\)\(\cdot\)\(1\)
Row 4\(\cdot\)\(2\)\(\cdot\)\(1\)\(\cdot\)\(\cdot\)\(1\)\(\cdot\)
Row 5\(1\)\(\cdot\)\(2\)\(\cdot\)\(1\)\(\cdot\)\(\cdot\)\(\cdot\)
Row 6\(\cdot\)\(1\)\(\cdot\)\(2\)\(\cdot\)\(1\)\(\cdot\)\(\cdot\)
Row 7\(\cdot\)\(\cdot\)\(1\)\(\cdot\)\(2\)\(\cdot\)\(1\)\(\cdot\)
Row 8\(\cdot\)\(\cdot\)\(\cdot\)\(1\)\(\cdot\)\(2\)\(\cdot\)\(1\)
  • \(J_{4,2}\widehat T_2=\widehat T_4J_{4,2}\)

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Evidence note from the source edition

Actual \(8\times8\) matrices. Dots are zero entries. The other entries are exact integers. Heavy lines mark the packet blocks: size four at level two and size two at level four.

The reordered operators and change of coordinates are

\[ \widehat T_N=R_NTR_N^{-1},\qquad J_{4,2}=R_4R_2^{-1}. \]

Multiplication cancels the intermediate coordinate maps:

\[ J_{4,2}\widehat T_2=\widehat T_4J_{4,2},\qquad J_{8,4}J_{4,2}=J_{8,2}. \]

Thus it makes no difference whether the operator is applied before or after a consistent coordinate change. One must transport the operator, not merely reuse the same numerical matrix under a new ordering.

Refined blocks still reconstruct the same map

A coarse block expands as

\[ P_bTP_a=\sum_{\beta\succ b,\,\alpha\succ a}P_\beta TP_\alpha. \]

The terms are maps embedded in the original source and target spaces. Adding their norms, or adding their matrix entries after forgetting the embeddings, is not this operator identity.

Read this as

The fine matrix contains a different block organization of the same operator. An independently guessed coarse matrix is a separate approximation problem, measured later by a defect.

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